RE: 9i DataGuard, RAC primary - secondary offline for networkmaintenance
- From: "Ric Van Dyke" <ric.van.dyke@xxxxxxxxxx>
- To: <cjpengel.dbalert@xxxxxxxxx>, <tony@xxxxxxxxxxxxxxx>
- Date: Tue, 5 Dec 2006 19:15:45 -0600
Carel-Jan,
You are very correct that as stated in the documentation the version of
Oracle are supposed to be the same (as in identical) on the primary and
the standby. However I worked with the folks who developed the standby
database code and this is more of a CYA requirement then a real one.
There was some long discussions about this requirement and I believe
that "paranoia" won out, the idea being it's better to be over
restrictive then not. The issue is more about the format of the redo
log stream then anything else. It's very likely that this setup will
work just fine. And given that Tony (apparently) has been running with
this setup for some period of time, it's again likely that this will
continue to work just fine.
The escape clause for Oracle should Tony run into bazaar problems will
likely be that the versions of Oracle are different in his
configuration. However I figure it's very unlikely that this will cause
an issue. Currently I agree that if your production system needs a
certain patch level then having a standby at a different patch level is
at least odd.
Ric Van Dyke
Hotsos Enterprises
-----------------------
Hotsos Symposium March 4-8, 2007. Be there.
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Carel-Jan Engel
Sent: Tuesday, December 05, 2006 5:46 PM
To: tony@xxxxxxxxxxxxxxx
Cc: oracle-l
Subject: Re: 9i DataGuard, RAC primary - secondary offline for
networkmaintenance
Hi Tony,
See inline
On Tue, 2006-12-05 at 22:09 +0000, Tony Sequeira wrote:
Hi all,
I have a 2 node 9i RAC primary (Win 2003), 9.2.0.6 mandated by the
application.
Have a physical standby 9.2.0.7.
All appears to be going well, teething problems over (touch wood).
Cross your fingers. Oracle DOESN'T support DG environments with
different versions. It appears you haven't checked the prerequisites
carefully enough.
Your standby database is not 9.2.0.7, mind that you never did a startup
migrate and ran catpatch.sql for 9.2.0.7 on the primary. Since your
standby is a physical copy of the primary, this database is 9.2.0.6 as
well. I don't know why you keep the standby (probably for High
Availability reasons), but switching/failing over to it might pop up
some surprises. 'Results are unpredictable' is the right phrase here. I
cannot emphasize enough that an HA configuration needs SYMMETRY. You're
violating this rule#1 here.
The primary is running in maximum performance mode.
The secondary server is due to go down for about 24 hours for absolutely
vital electrical maintenance work.
I believe that this will be OK, and that the secondary will catch up
when brought online again.
Yes, no problem. Not that you can use it, effectively it is unavailable
as long as you have this mixed version setup running. I have never
investigated the combination of a failover/switchover with startup
migrate/run catpatch. It might work. Please test it and share your
experiences.
There is one big assumption involved in your theory: You have to keep
the archived redo log files long enough for the standby to fetch them
after it switched on again, As Ric Van Dyke posted while I am writing
this.
Any think or know different? I'm trying to plan for any glitches now,
the primary database is a vital 24/7 system.
If so, either upgrade your primary to 9.2.0.7 or install 9.2.0.6 at the
standby. You don't want surprises at the eve of failover with a vital
24x7 system.
I am aware of Note:259804.1 - particularly the section 'Real
Application Clusters and Data Guard Redo Apply During a Network
Outage'.
Get aware of
http://download-uk.oracle.com/docs/cd/B10501_01/server.920/a96653/consid
erations.htm#52221 , 3rd bullet, too.
Best regards,
Carel-Jan Engel
===
If you think education is expensive, try ignorance. (Derek Bok)
===
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